Cationic polysaccharides and other polymers have been used widely in personal care and household products to perform a function in the final product, ranging from thickening to conditioning of a substrate. Depending on the application, the substrate can be skin, hair, or textile substrates.
Cationic polysaccharides are used in haircare products to provide conditioning to the hair. In skincare products, these same polymers can provide conditioning effects to the skin. When incorporated into detergent and fabric softening formulations, these same polymers can provide conditioning, softening, and antistatic characteristics to fabrics.
Hair conditioning agents perform their functions at the cuticle, or outer sheath of keratinized scales on the surface of the hair fiber. The cuticle's scales are arranged in overlapping fashion like the shingles on a roof. The cell structure of the cuticle is composed of an A layer, the exocuticle, and a B layer, the endocuticle. The clear outer A layer, composed of sulfur-containing proteins, protects the hair from chemical, physical, and environmental damage. Consequently, the condition of the cuticle determines the condition of the hair, and hair-conditioning products are directed toward enhancing and restoring the cuticle shaft layer. An intact cuticle is responsible for the strength, shine, softness, smoothness, and manageability of hair. (Conditioning Agents for Hair & Skin, Ed. R. Schueller and P. Romanowski, Marcel Dekker, Inc., NY, N.Y., 1999.)
Wet and dry combability measurements are typical test methods used to measure conditioning performance in shampoo and conditioner applications. Commercial cationic conditioning polymers in the marketplace have been reported to reduce the wet combing force experienced on combing wet hair by 30%–50% relative to the shampoo containing no polymer. The performance of different cationic polymers in these applications has been found to be lacking, however, in achieving a good balance of wet and dry combing force reduction, with good optical clarity in a formulation.
For example, cationic polygalactomannans, including cationic guars, have been shown to deliver outstanding wet and dry comb force reduction when incorporated into a shampoo. However, cationic guars have been found to be lacking in their ability to deliver formulations with clarity (P. Hossel et al, Int. J. Cosmetic Science, 2000, v. 22, 1–10). Cationic celluloses have been found to deliver good clarity in cleansing surfactant systems, but others have found them to be lacking a good balance of clarity and wet and dry combing force reduction (P. Hossel et al, Int. J. Cosmetic Science, 2000, v. 22, 1–10).
Historically, only high molecular weight cationic polymers have been used in cleansing products, and it has been suggested that only high molecular weight cationic polymers can deliver the conditioning effect desired in cleansing systems (V. Andre{grave over ( )}, R. Norenberg, J. Rieger, P. Hoessel, Proceedings, XXIst IFSCC International Congress 2000, Berlin, p. 189–199). For practical purposes high molecular weight cationic guar is defined as having a typical lower molecular weight limit of about 400,000 Daltons. However, the high molecular weight cationic guar conditioning polymers, available in the marketplace, have their drawbacks, such as incompatibility with surfactant systems used in shampoo, bodywash, conditioners, etc. In addition, they contribute to the final product viscosity, which may not be desirable. High molecular weight cationic guar polymers are also known to be difficult to disperse and dissolve in aqueous solution.
As mentioned above, cationic polymers vary in their ability to deliver good conditioning and clarity in personal care and household product formulations. Cationic guars are known to deliver good conditioning when incorporated into cleansing surfactant systems such as shampoo formulations. Insoluble matter in cationic guars and the incompatibility of high molecular weight cationic guars with surfactants in the formulation, however, can lead to unstable and opaque products. Since the conditioning performance of the polymer is strongly related to its solubility in and its interaction with the surfactants in these systems, the degree of this interaction influences both the conditioning performance of the polymer and the clarity of the system.
The desire for clarity in a formulation varies with manufacturers and consumers. In the past several years, there has been a continuing trend in the marketplace toward clear personal care and household products.
U.S. Pat. No. 6,210,689 B1 discloses the use of an amphoteric guar gum composition that contains cationic and anionic groups attached to its backbone for treating keratin substances. This composition is used in aqueous systems of cosmetics such as shampoos, topical sprays, dental care products and products containing fragrances and/or antimicrobial agents.
U.S. Pat. No. 5,756,720 describes a process for producing a polygalactomannan composition having nonionic and cationic groups attached to the backbone. This patent describes the achievement of high optical clarity in cleansing surfactant formulations with this composition. The hydroxypropyl cationic polygalactomannans of this composition, however, have been found lacking in conditioning performance, as described in WO 99/36054.
U.S. Pat. No. 5,489,674 describes a process for preparing polygalactomannan gum and a polygalactomannan gum composition prepared by a specific process that includes aqueous alcohol processing. The product is described as giving 85–100% transmittance at wavelengths between 500–600 nm at 0.5 part polymer in 100 parts of an aqueous solution. The use of this material in personal care applications is disclosed.
JP Application Hei 10 [1998]-36403 discloses a cosmetic composition that uses a polygalactomannan degradation product that has 80% or higher of its molecular weight distribution within the range of 4,500 to 35,000 for use in hair and skin care products.
Cationic HEC, such as Ucare Polymer JR400™ having a high cationic substitution is known to give good clarity in a broad range of surfactant systems. However, this polymer has also been cited by the manufacturer as causing “buildup” problems after repeated use. One manufacturer has recommended the use of cationic HEC having lower cationic substitution levels to eliminate buildup issues (“Cationic Conditioners that Revitalize Hair and Skin”, Amerchol Product Literature, WSP801, July, 1998). Buildup has been defined by this manufacturer as the binding of a polymer to a substrate, making it more difficult to remove the polymer from the substrate in subsequent cleansing treatments.
The lower substitution level on cationic HEC does reduce buildup, however, these polymers lack broad surfactant compatibility (“Cationic Conditioners that Revitalize Hair and Skin”, Amerchol Product Literature, WSP801, July 1998).
A need still exists in the marketplace for a cationic conditioning polymer that has broad surfactant compatibility, and can deliver clear personal care and household formulations with good conditioning performance.